Water cooled screw compressor

ABSTRACT

A water cooled rotary screw compressor system.

BACKGROUND

The present application relates generally to a water injected screw compressor including cooperating rotors. More particularly, the present application relates to rotary screw compressor adapted to deliver oil free air from a water cooled compression chamber.

SUMMARY

One embodiment of the present application is a unique water cooled screw compressor. Another embodiment is a rotary screw compression system. Other embodiments include methods, systems, apparatuses, devises, hardware and combinations for rotary screw compressors. Further embodiments, forms, features, aspects, benefits and advantages of the present application will become apparent from the description and figures provided herewith.

DESCRIPTION OF THE DRAWINGS

The description herein makes reference to the accompanying drawings wherein like reference numeral refer to like parts throughout several views and wherein:

FIG. 1 schematically illustrates one embodiment of a compressor unit.

FIG. 2 schematically illustrates one embodiment of a single stage rotary screw compression system of the present invention.

FIG. 3 schematically illustrates another embodiment of a single stage rotary screw compression system of the present invention.

FIG. 4 schematically illustrates one embodiment of a two stage rotary screw compression system of the present invention.

FIG. 5 is an illustrative sectional view of one embodiment of a single stage rotary screw compressor of the present application.

FIG. 6 is an illustrative cross sectional view of a mate rotor and a female rotor.

DETAILED DESCRIPTION

For purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.

With reference to FIG. 1, there is schematically illustrated a compressor unit 10. The compressor unit 10 utilizes a rotary screw compressor to pressurize the working fluid introduced therein through an inlet into a suction side inlet of the rotary screw compressor. In one form the pressurized working fluid is processed post pressurization within the rotary screw compressor in a separator to withdraw contaminates such as moisture from the working fluid. The pressurized working fluid is discharged from the rotary screw compressor via a compressed working fluid line. The compressor unit 10 contemplated herein may be a mobile or stationary device. The working fluid is preferably ambient air introduced into the compressor unit 10.

The compressor unit 10 is coupled via a working fluid outlet to an inlet of machinery and/or equipment utilizing the compressed working fluid. In one form the compressed working fluid is disposed in fluid communication with a user's compressed working fluid network. In one aspect the present application is directed to the delivery of pressurized oil free working fluid from an oil free compression chamber environment. More specifically, the compression chamber which houses the rotatable rotors is free of oil and oil related materials whether considered a petrochemical based oil or a synthetic based oil. The term as utilized herein is intended to refer generally to a class of lubricants that are either petroleum or synthetic based and have a variety of viscosities; non limiting examples include grease or oil. The working fluid entering the compression chamber of the rotary screw compressor undergoes a pressure rise based upon the work of the screw compressor rotors and is not exposed to oil and therefore the working fluid exits the rotary screw compressor with no increase in oil content. In a preferred form of the present application the working fluid entering the suction side of the rotary compressor is free of oil.

With reference to FIG. 2, there is schematically illustrated a single stage rotary screw compressor system 12. The rotary screw compressor system 12 includes a rotary screw compressor 17 having a male and female screw rotor that are disposed within a bore/working fluid chamber in the compressor housing. A power source 13 is coupled with the male and female screw rotors through a gear system 14 and provides the rotational power to drive the pair of screw rotors. In one form the power source 13 is an electric motor, however the present application contemplates that the power source could include an internal combustion engine, a turbine or other modes of providing power. In one form a controller 15 is operatively coupled with the compressor unit 10 to control the operating parameters thereof.

In the single stage rotary screw compressor 17 there is contemplated a variety of pressure ratios: in one form of the present application the pressure ratio when the working fluid is air is about 8:1 and in another form of the present application the pressure ratio is about 10:1. However, the present application is not intended to be limited to the preceding pressure ratios unless specifically stated to the contrary. In one form of the present application the ambient working fluid entering the bore/working fluid chamber within the compressor housing is subjected to a pressure rise commensurate with a pressure ratio of 10:1 and the male and female screw rotors are driven by the power source 13 at a rotational speed of about 10,000 revolutions-per-minute (RPM). The pressure rise from the work performed by the rotors on the working fluid causes a temperature increase of the working fluid. A temperature control system 16 is disposed in fluid communication with the bore/working fluid chamber to control the temperature of the working fluid.

The temperature control system 16 includes a source 18 for water that is delivered through at least one supply conduit 19 to the bore/working fluid chamber within the compressor housing. In one form the water is delivered directly into the bore/working fluid chamber, and in a preferred form the water is delivered to the male and female screw rotors that are working on the working fluid. In one form of the present application the water is clean water so as to be substantially free of contaminants and minerals. In another form of the present application the water is potable water. The present application further contemplates embodiments of the present application that may utilize water that includes additives; a preferred form of additives being non-toxic. In one form the quantity of water delivered into the bore/working fluid chamber is sufficient to remove a portion of the quantity of heat emitted into the working fluid from the heat of compression without flooding the bore/working fluid chamber. The applicants have found that in one form of the present application a comparison of the quantity of water contemplated for the present application and a flooded system is on the order of no more than about five percent (5%) of the amount of water utilized in a water flooded system. One aspect of the present application facilitates the removal of the portion of the heat of compression from the working fluid to have the discharge temperature of the pressurized working fluid to be at a temperature level useable by the end user without requiring additional cooling. In one non limiting example the desired maximum temperature for the discharged working fluid is about 250 degrees Fahrenheit However, the present application contemplates some systems where the end user desires additional cooling.

The present application contemplates that the water delivered to the bore/working fluid chamber can be either steady, non steady state or pulsed. Further, the present application contemplates that a parameter of the working fluid could be sensed or monitored and based upon the outcome of this sensing or monitoring the delivery of cooling water to the bore/working fluid chamber could be adjusted. Therefore, in another form of the present application there is contemplated a temperature control system having a feedback loop based upon a sensed or monitored parameter to adjust the amount of water delivered. In one form of the present application, looking at a sensed or monitored parameter of the temperature of the discharge working fluid is monitored and the quantity of water delivered to the bore/working fluid chamber is adjusted to compensate for the amount of heat that is desired to be removed to meet a target temperature. The present application contemplates that other parameters could be looked at for utilization in the feedback loop such as the discharge pressure of the working fluid and then translated through a table or algorithm.

With reference to FIG. 3, there is illustrated an alternate embodiment of a single stage rotary screw compressor system 112. The single stage rotary screw compressor system 112 is substantially identical with the single stage rotary screw compressor system 12 with exception being the elimination of the gear system 14. The power source 13 is directly coupled to the single stage rotary screw compressor 17 and is adapted to drive the male and female rotors free of the intermediate year set 14.

With reference to FIG. 4, there is schematically illustrated a two stage rotary screw compressor system 30. The two stage rotary screw compressor system 30 includes a first rotary screw compressor 31 having a mate and female screw rotor that are disposed within a bore/working fluid chamber in the compressor housing and a second rotary screw compressor 32 having a male and female screw rotor that are disposed within a second bore/working fluid in a compressor housing. A power source 33 is coupled with the first rotary screw compressor 31 through a gear system 34 and provides the rotational power to drive the pair of screw rotors in the first rotary screw compressor 31. A second power source 35 is coupled with the second rotary screw compressor 32 through a gear system 36 and provides the rotational power to drive the pair of screw rotors in the second rotary screw compressor 32. The present application contemplates a shared power source for the pair of rotary screw compressors 31 and 32. In one form the power sources 33 and 35 are an electric motors, however the present application contemplates that the power source could include an internal combustion engine, a turbine or other modes of providing power. In one form a controller 15 is operatively coupled with the compressor unit 30 to control the operating parameters thereof.

In the two stage rotary screw compressor system 30 there is contemplated a variety of pressure ratios for each of the first rotary screw compressor 31 and the second rotary screw compressor 32. In one form of the present application the first rotary screw compressor 31 operates at about nine thousand RPM and the pair of rotors are drivers at this speed and the second rotary screw compressor 32 operates at about fifteen thousand RPM and the pair of rotors are driven at this speed. The pressure rise from the work performed by the first rotary screw compressor 31 causes a temperature increase in the working fluid.

The temperature control system 16 includes a source 18 for water that is delivered through supply conduits 19 and 19 a to the respective bore/working fluid chambers within the compressor housings. In one form the water is delivered directly into the bore/working fluid chamber of the first rotary screw compressor 31, and in a preferred form the water is delivered to the male and female screw rotors that are working on the working fluid. In one form of the present application the water is clean water so as to be substantially free of contaminants and minerals. In another form of the present application the water is potable water. The present application further contemplates embodiments of the present application that may utilize water that includes additives. In one form the quantity of water delivered into the bore/working fluid chamber is sufficient to remove a portion of the quantity of heat emitted into the working fluid from the heat of compression without flooding the bore/working fluid chamber. The applicants have found that in one form of the present application a comparison of the quantity of water contemplated for the present application in the first rotary screw compressor and a flooded system is on the order of no more than about five percent (5%) of the amount of water utilized in a water flooded system. One aspect of the present application facilitates the removal of the portion of the heat of compression from the working fluid to have the discharge temperature of the pressurized working fluid to be at a predetermined temperature level acceptable for introduction into the second rotary screw compressor 32.

The present application contemplates that the water delivered to the bore/working fluid chamber can be either steady, non steady state or pulsed. Further, the present application contemplates that a parameter of the working fluid could be sensed or monitored and based upon the outcome of this sensing or monitoring the delivery of cooling water to the bore/working fluid chamber could be adjusted. Therefore, in another form of the present application there is contemplated a temperature control system having a feedback loop based upon a sensed or monitored parameter to adjust the amount of water delivered. In one form of the system looking at a sensed or monitored parameter the temperature of the discharge working fluid is monitored and the quantity of water delivered to the bore/working fluid chamber is adjusted to compensate for the amount of heat that is desired to be removed to meet a target temperature. The present application contemplates that other parameters could be looked at for utilization in the feedback loop such as the discharge pressure of the working fluid and then translated through a table or algorithm.

In one form the water is delivered directly into the bore/working fluid chamber of second rotary screw compressor 32, and in a preferred form the water is delivered onto the male and female screw rotors that are working on the working fluid. In one form of the present application the water is clean water so as to be substantially free of contaminants and minerals. In another form of the present application the water is potable water. The present application further contemplates embodiments of the present application that may utilize water that includes additives. In one form the quantity of water delivered into the bore/working fluid chamber is sufficient to remove a portion of the quantity of heat emitted into the working fluid from the heat of compression without flooding the bore/working fluid chamber. The applicants have found that in one form of the present application a comparison of the quantity of water contemplated for the present application in the first rotary screw compressor and a flooded system is on the order of no more than about five percent (5%) of the amount of water utilized in a water flooded system. One aspect of the present application facilitates the removal of the portion of the heat of compression from the working fluid to have the discharge temperature of the pressurized working fluid to be at a predetermined temperature level useable by the end user. In one non limiting example the desired maximum temperature for the discharged working fluid is about 250 degrees Fahrenheit.

The present application contemplates that the water delivered to the bore/working fluid chamber can be either steady, non steady state or pulsed. Further, the present application contemplates that a parameter of the working fluid could be sensed or monitored and based upon the outcome of this sensing or monitoring the delivery of cooling water to the bore/working fluid chamber could be adjusted. Therefore, in another form of the present application there is contemplated a temperature control system having a feedback loop based upon a sensed or monitored parameter to adjust the amount of water delivered. In one form of the system looking at a sensed or monitored parameter the temperature of the discharge working fluid is monitored and the quantity of water delivered to the bore/working fluid chamber is adjusted to compensate for the amount of heat that is desired to be removed to meet a target temperature. The present application contemplates that other parameters could be looked at for utilization in the feedback loop such as the discharge pressure of the working fluid and then translated through a table or algorithm.

With further reference to FIG. 4, there is illustrated an optional intercooler 40 that may be utilized to cool the discharge working fluid from the first rotary screw compressor 31 prior to entry into the second rotary screw compressor 32. The second rotary screw compressor 32 may than utilize the above described cooling system to deliver working fluid at a predetermined temperature to the end user.

With reference to FIG. 5, there is illustrated an illustrative sectional view of a single stage rotary screw compressor 50. The single stage rotary screw compressor 50 includes a male screw rotor 51 and a female screw rotor 52. Power source 13 is coupled with the male screw rotor 51 and the female screw rotor 52 through a gear system 14 and provides the rotational power to drive the pair of screw rotors. In one form the power source 13 is an electric motor, however the present application contemplates that the power source could include an internal combustion engine, a turbine or other modes of providing power. In an alternate form of the present application the gear system 14 is not present and the power source 13 is coupled directly to the rotors 51 and 52.

The single stage rotary screw compressor 50 includes a housing 53 with a bore/working fluid chamber 54. Disposed within the bore/working fluid chamber 54 is the male screw rotor 51 and the female screw rotor 52. The inner surface 70 of the bore/working fluid chamber 54 includes a abradable coating 71 to facilitate a seal between the outer periphery of the respective rotors and the inner surface 70 of the bore/working fluid chamber 54. The face of the rotors 51 a and 52 a include an abradable coating for providing a seal to the regions as the working fluid undergoes an increase in pressure. In one form of the present application the abradable coating is a polymer coating. The bore/working fluid chamber 54 is free from oil and oil related materials and the working fluid passing through the bore/working fluid chamber 54 does not have oil or oil related materials imparted thereto. The male and female rotors rotate on bearings 60 that include oil and/or oil related lubricants. One of skill in the art wilt fully understand that the bearings are lubricated with an oil related product that includes materials such as grease. The bearings 60 and the associated oil products in the bearing housings 62 are isolated from the bore/working fluid chamber 54 by seals 61. The seals 61 seal along the shafts of the rotors 51 and 52 and maintain the oil and oil related materials within the bearing housings and prevent the contamination of the working fluid within the bore/working fluid chamber 54. The working fluid passing through and pressurized with the bore/working fluid chamber 54 emerges free from the addition of any oil or oil related material.

As discussed previously, the temperature control system includes a source 18 for water that is delivered through at least one supply conduit 19 to the bore/working fluid chamber 54 within the compressor housing 53. In one form the water is delivered directly into the bore/working fluid chamber 54, and in a preferred form the water is delivered to the male and female screw rotors 51, 52 that are working on the working fluid. In one form of the present application the water is clean water so as to be substantially free of contaminants and minerals. In another form of the present application the water is potable water. The present application further contemplates embodiments of the present application that may utilize water that includes additives. In one form the quantity of water delivered into the bore/working fluid chamber is sufficient to remove a portion of the quantity of heat emitted into the working fluid from the heat of compression without flooding the bore/working fluid chamber 54. The applicants have found that in one form of the present application a comparison of the quantity of water contemplated for the present application and a flooded system is on the order of no more than about five percent (5%) of the amount of water utilized in a water flooded system. One aspect of the present application facilitates the removal of the portion of the heat of compression from the working fluid to have the discharge temperature of the pressurized working fluid to be at a temperature level useable by the end user. In one non limiting example the desired maximum temperature for the discharged working fluid is about 250 degrees Fahrenheit.

The present application contemplates that the water delivered to the bore/working fluid chamber can be either steady, non steady state or pulsed. Further, the present application contemplates that a parameter of the working fluid could be sensed or monitored and based upon the outcome of this sensing or monitoring the delivery of cooling water to the bore/working fluid chamber could be adjusted. Therefore, in another form of the present application there is contemplated a temperature control system having a feedback loop based upon a sensed or monitored parameter to adjust the amount of water delivered. In one form of the system looking at a sensed of monitored parameter the temperature of the discharge working fluid is monitored and the quantity of water delivered to the bore/working fluid chamber is adjusted to compensate for the amount of heat that is desired to be removed to meet a target temperature. The present application contemplates that other parameters could be looked at for utilization in the feedback loop such as the discharge pressure of the working fluid and translated through a table or algorithm.

With reference to FIG. 6, there is illustrated an illustrative cross sectional view of a male screw rotor 100 and a female screw rotor 101.

Embodiments of the present invention include rotary screw compressor system, comprising:

a housing including a surface defining at least a portion of an internal working fluid volume free of oil, at least a portion said surface including an abradable coating;

a first pair of oil lubricated bearings;

a second pair of oil lubricated bearings;

a male screw rotor rotatable on said first pair of oil lubricated bearings, said male screw rotor having a first outer surface disposed within said internal working volume;

a female screw rotor rotatable on said second pair of oil lubricated bearings, said female screw rotor having a second outer surface disposed within said internal working volume and intermeshing with said male rotor, at least one of said outer surfaces including a second abradable coating;

a power source coupled with an operable to rotate said rotors;

a temperature controller in fluid communication with said internal working fluid volume and operable to deliver a quantity of water to the working fluid within the internal working fluid volume to remove a portion of the heat of compression to obtain a predetermined discharge temperature for the working fluid without flooding the internal working fluid volume; and

wherein the internal working fluid volume is isolated from said oil lubricated bearings to isolate the working fluid from oil contamination.

In a refinement the rotary screw compressor system includes that the temperature controller delivers a continuous spray of water onto at least one of said rotors.

In another refinement the rotary screw compressor system includes that the temperature controller delivers a continuous spray of water onto both of said rotors.

In yet another refinement the rotary screw compressor system includes that the quantity of water delivered to the working fluid within said internal working fluid volume is no more than about five percent of the quantity of water necessary to define a flooded environment.

In yet further refinement the rotary screw compressor system includes that the quantity of water delivered to the working fluid within said internal working fluid volume is within a range of about two percent to four percent of the quantity of water that would be necessary to define a flooded environment.

In yet further refinement the rotary screw compressor system includes that the compression ratio is about 10:1.

In yet further refinement the rotary screw compressor system includes that the compression ratio is about 8:1.

In yet further refinement the rotary screw compressor system includes that the quantity of water delivered to the working fluid within said internal working fluid volume is no more than five percent of the quantity of water that would be utilized to define a flooded environment,

wherein said temperature controller includes a volume of clean water;

wherein the compression ratio is at least about 8:1; and

wherein said predetermined discharge temperature is about 250° F.

In yet another refinement the rotary screw compressor includes that the volume of clean water is defined by potable water.

In yet another refinement the rotary screw compressor system includes that the compression ratio is about 10:1; and wherein said male and female rotors are driven at about 10,000 RPM.

Embodiments of the present invention include rotary screw compression system, comprising:

a power source:

a rotary screw compressor having a housing with a male and a female rotor rotatably disposed therein, said rotors driven by said power source to increase the pressure ration of an oiless working fluid, at least one of said rotors include a sealing coating; and

a cooling system disposed in fluid communication with said rotors and operable to deliver a dose of water to at least one of said rotors, said dose being about five percent of the dose of water required to define a flooded environment.

In a refinement the rotary screw compression system includes that the dose is a continuous stream of water, and the working fluid is air.

In yet another refinement the rotary screw compression system includes that the dose is a pulsed stream of water, and the working fluid is air.

In yet another refinement the rotary screw compression system includes that the dose keeps the discharge temperature of the working fluid below 250 degrees Fahrenheit.

In yet another refinement the rotary screw compression system further includes a sensor for sensing the temperature of the working fluid at the discharge of said rotary screw compressor; and

said dose is dependent upon the temperature at the discharge of said rotary screw compressor.

In yet another refinement the rotary screw compression system includes that the rotary screw compressor is the sole mechanism for compression.

In yet another refinement the rotary screw compression system is limited to a single stage of compression.

In yet another refinement the rotary screw compression system includes that the dose is a continuous stream of water;

the working fluid is defined by air;

wherein said dose keeps the discharge temperature of the working fluid below a predetermined value of 250 degrees Fahrenheit; and

which further includes a sensor for sensing the temperature of the working fluid at the discharge of rotary screw compressor; and

said dose is dependent upon the temperature at said sensor.

In yet another refinement the rotary screw compression system includes only a single stage of compression.

In yet another refinement the rotary screw compression system includes that the dose is a pulsed stream of water;

the working fluid is defined by air;

wherein said dose keeps the discharge temperature of the working fluid below 250 degrees Fahrenheit;

which further includes a sensor for sensing the temperature of the working fluid at the discharge of said rotary screw compressor; and

said dose is dependent upon the temperature at said sensor.

In yet another refinement the rotary screw compression system further includes a second rotary screw compressor with a second male and a second female rotor disposed therein, said rotors operable to increase the pressure ratio of an oiless working fluid delivered from said rotary screw compressor.

While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment(s), but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as permitted under the law. Furthermore it should be understood that while the use of the work preferable, preferably, or preferred in the description above indicates that feature so described may be more desirable, it nonetheless may not be necessary and any embodiment lacking the same may be contemplated as within the scope of the invention, that scope being defined by the claims that follow. In reading the claims it is intended that when works such as “a,” “an” “at least one” and “at least a portion” are used, there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. Further, when the language “at least a portion” and/or “a portion” is used the item may include a portion and/or the entire item unless specifically stated to the contrary. 

What is claimed is:
 1. A rotary screw compressor system, comprising: a housing including a surface defining at least a portion of an internal working fluid volume free of oil, at least a portion said surface including an abradable coating; a first pair of oil lubricated bearings; a second pair of oil lubricated bearings; a male screw rotor rotatable on said first pair of oil lubricated bearings, said male screw rotor having a first outer surface disposed within said internal working volume; a female screw rotor rotatable on said second pair of oil lubricated bearings, said female screw rotor having a second outer surface disposed within said internal working volume and intermeshing with said male rotor, at least one of said outer surfaces including a second abradable coating; a power source coupled with and operable to rotate said rotors; a temperature controller in fluid communication with said internal working fluid volume and operable to deliver a quantity of water to the working fluid within the internal working fluid volume to remove a portion of the heat of compression to obtain a predetermined discharge temperature for the working fluid without flooding the internal working fluid volume; and wherein the internal working fluid volume is isolated from said oil lubricated bearings to isolate the working fluid from oil contamination.
 2. The rotary screw compressor system of claim 1, wherein said temperature controller delivers a continuous spray of water onto at least one of said rotors.
 3. The rotary screw compressor system of claim 1, wherein said temperature controller delivers a continuous spray of water onto both of said rotors.
 4. The rotary screw compressor system of claim 1, wherein the quantity of wafer delivered to the working fluid within said internal working fluid volume is no more than about five percent of the quantity of water necessary to define a flooded environment.
 5. The rotary screw compressor system of claim 4, wherein the quantity of water delivered to the working fluid within said internal working fluid volume is within a range of about two percent to four percent of the quantity of water that would be necessary to define a flooded environment. 6 The rotary screw compressor system of claim 1, wherein the compression ratio is about 10:1.
 7. The rotary screw compressor system of claim 1, wherein the compression ratio is about 8:1.
 8. The rotary screw compressor system of claim 1, wherein the quantity of water delivered to the working fluid within said internal working fluid volume is no more than five percent of the quantity of water that would be utilized to define a flooded environment, wherein said temperature controller includes a volume of clean water; wherein the compression ratio is at least about 8:1; and wherein said predetermined discharge temperature is about 250° F.
 9. The rotary screw compressor system of claim 8, wherein the volume of clean water is defined by potable water.
 10. The rotary screw compressor system of claim 8, wherein the compression ratio is about 10:1; and wherein said male and female rotors are driven at about 10,000 RPM.
 11. A rotary screw compression system, comprising: a power source; a rotary screw compressor having a housing with a male and a female rotor rotatably disposed therein, said rotors driven by said power source to increase the pressure ratio of an oiless working fluid, at least one of said rotors include a sealing coating; and a cooling system disposed in fluid communication with said rotors and operable to deliver a dose of water to at least one of said rotors, said dose being about five percent of the dose of water required to define a flooded environment.
 12. The rotary screw compression system of claim 11, wherein said dose is a continuous stream of water, and the working fluid is air.
 13. The rotary screw compression system of claim 11, wherein said dose is a pulsed stream of water, and the working fluid is air.
 14. The rotary screw compression system of claim 11, wherein said dose keeps the discharge temperature of the working fluid below 250 degrees Fahrenheit.
 15. The rotary screw compression system of claim 11, which further includes a sensor for sensing the temperature of the working fluid at the discharge of said rotary screw compressor; and said dose is dependent upon the temperature at the discharge of said rotary screw compressor.
 16. The rotary screw compression system of claim 11, wherein said rotary screw compressor is the sole mechanism for compression.
 17. The rotary screw compression system of claim 11, which is limited to a single stage of compression.
 18. The rotary screw compression system of claim 11, wherein said dose is a continuous stream of water; the working fluid is defined by air; wherein said dose keeps the discharge temperature of the working fluid below a predetermined value of 250 degrees Fahrenheit; and which further includes a sensor for sensing the temperature of the working fluid at the discharge of rotary screw compressor; and said dose is dependent upon the temperature at said sensor.
 19. The rotary screw compression system of claim 18, wherein there is only a single stage of compression.
 20. The rotary screw compression system of claim 11, wherein said dose is a pulsed stream of wafer; the working fluid is defined by air; wherein said dose keeps the discharge temperature of the working fluid below 250 degrees Fahrenheit; which further includes a sensor for sensing the temperature of the working fluid at the discharge of said rotary screw compressor; and said dose is dependent upon the temperature at said sensor.
 21. The rotary screw compression system of claim 20, wherein there is only a single stage of compression.
 22. The rotary screw compression system of claim 11, which further includes a second rotary screw compressor with a second male and a second female rotor disposed therein, said rotors operable to increase the pressure ratio of an oiless working fluid delivered from said rotary screw compressor. 